Modem communications networks often include a number of paths or links that are interconnected to route voice, video, and/or data (hereinafter collectively referred to as "data") traffic from one location of the network to another. At each location, an interconnect node couples a plurality of source nodes and destination nodes to the network. In some cases, the sources and destinations are incorporated in a private line network that may include a series of offices connected together by leased-lines with switching facilities and transmission equipment owned and operated by the carrier or service provider and leased to the user. This type of network is conventionally referred to as a "circuit-switching network." Accordingly, a source node of one office at one location of the network may transmit data to a destination node of a second office located at another location of the network through their respective switching facilities.
At any given location, a large number of source nodes may desire to communicate through their respective switching facilities, or interconnect node, to destination nodes at various other locations of the network. The data traffic from the various source nodes is first multiplexed through the source switching facility, then demultiplexed at the destination switching facility and finally delivered to the proper destination node. A variety of techniques for efficiently multiplexing data from multiple source nodes onto a single circuit of the network are presently employed in private line networks. For instance, time division multiplexing ("TDM") affords each source node full access to the allotted bandwidth of the circuit for a small amount of time. The circuit is divided into defined time segments, with each segment corresponding to a specific source node, to provide for the transfer of data from those source nodes, when called upon, through the network.
Other data communications systems, in contrast, have not been as successful employing multiplexing techniques to enhance network efficiency further. In particular, frame-relay networks offer far fewer alternatives than their circuit-switching network counterparts. Frame-relay networks are often referred to as "packet-switching networks." Packet-switching networks, as opposed to circuit-switching networks, allow multiple users to share data network facilities and bandwidth rather than providing a specific amount of dedicated bandwidth to each user, as in TDM. Instead, packet switches divide bandwidth into connectionless, virtual circuits. As is known, virtual circuit bandwidth is consumed only when data is actually transmitted. Otherwise, the bandwidth is not used. In this way, packet-switching networks essentially mirror the operation of a statistical multiplexer (whereby multiple logical users share a single network access circuit).
One problem, however, with such traditional virtual circuits relates to the throughput efficiency in frame-relay and other packet-switching networks. For instance, a one-to-one correspondence exists between applications and frame-relay virtual circuits, there being no inherent mechanism in today's frame-relay standards for transporting end-to-end data management. Internet Engineering Task Force Request for Comments ("ETF RFC") 1490 "Multiprotocol Interconnect Over Frame Relay," herein incorporated by reference, provides the ability to multiplex protocols, but forces the end-to-end data management data and the data communicated on to a single logical channel on a given virtual circuit. Additionally, IETF RFC 1490 protocol headers appear on every single frame transmitted over the circuit.
A second problem with traditional frame relay networks is that they are limited by the data rates that are achievable. Specifically, in order to achieve data transmission rates greater than 1.5 Mbps (mega bits per second), most network service providers use Asynchronous Transfer Mode (ATM) which can provide data transmission rates of up to 44 Mbps. However, current data transmission using an ATM network or a hybrid ATM/frame relay network is without acceptable systems and methods to perform diagnostics that are compatible with existing frame relay networks across the virtual circuit.